1) Field of the Invention
This invention relates to a method for forming a thin film and a method for manufacturing a thin film magnetic head. These methods are usable for alignment of two thin film elements to be formed at different stacking positions in a thin film magnetic head. Moreover, these methods are usable for forming a high density wire pattern in various circuit elements and integrated circuits.
2) Description of Related Art
It is well known that thin film magnetic heads for magnetic disk driving device constituting a computer memory have multilayered structures, and are manufactured, on a wafer, by film-forming techniques such as sputtering or plating and high precise patterning techniques such as photolithography, wet-etching and dry-etching.
In manufacturing a thin film magnetic head, various thin film elements to be formed at different stacking positions are required to be aligned precisely. In a composite type thin film magnetic head as a typical example, a writing element and a MR reading element are required to be aligned precisely.
Conventionally, the alignment is carried out as follows: A pattern for a first marker is formed on a mask to define a first thin film element pattern (e.g., a reading element pattern). Then, the first thin film element and the first marker are formed on a support at the same time. The marker forming technique is described in Kokai Publication Kokai Hei 10-162316 (JP A 10-162316), for example.
Then, an optical transparent film (a flat film) is formed, of Al2O3 or SiO2 on the support so as to cover the first thin film element and the first marker.
Subsequently, the optical transparent film is flattened, and on the flattened surface is formed a second marker on the basis of the first marker.
Then, a thin film to constitute a second thin film element (e.g., a writing element) is formed on the optical transparent film. The thin film, which is optically opaque, is generally made of a magnetic material.
Subsequently, the thin film is patterned by a photolithography process to form the second thin film element. Since the thin film is optically opaque, the photolithography process is carried out on the basis of the second marker.
In the above conventional manufacturing method, there is the problem that since the photolithography process is carried out on the basis of the second marker which is formed on the basis of the first marker, not directly on the basis of the first marker having precise alignment for the first thin film element, the alignment precision of the second thin film element for the first thin film element is degraded.
It is an object of the present invention to provide a method for forming a thin film and a method for manufacturing a thin film magnetic head which can align the first and second thin film elements to be formed at the different stacking positions precisely and stably.
For achieving the above object, this invention is directed at four type of forming methods of a thin film.
 less than First Type of forming method greater than 
The first type of forming method includes the following steps.
First of all, an optical transparent film is formed on a support so as to cover a first thin film element and marker on the support, and then, flattened.
Subsequently, a resist-cover is formed on the part of the optical transparent film above the marker by a photolithography process. Thereafter, a plate underfilm is formed on the optical transparent film and the resist-cover, and the resist-cover is removed from the optical transparent film.
Next, a resistframe is formed on the part of the optical transparent film including the plate underfilm above the first thin film element on the basis of the marker which is visible from the removed area of the resist-cover via the optical transparent film. Since the resist-cover and the part of the plate underfilm thereon are removed from on the optical transparent film, an exposing apparatus can recognize the marker via the optical transparent film. Therefore, the photolithography process to form the resistframe can be performed on the basis of the marker visible via the optical transparent film. As a result, the resistframe can be aligned for the first thin film element precisely and stably.
Thereafter, a plate film is formed on the part of the plate underfilm enclosed by the resistframe. After the resistframe is removed, the plate underfilm is patterned alongside the pattern of the plate film. As a result, the patterned plate film can be aligned for the first thin film element precisely and stably.
 less than Second type of forming method greater than 
The second type of forming method includes the following steps.
First of all, an optical transparent film is formed on a support so as to cover a first thin film element and a first marker on the support, and then, flattened.
Then, a second marker is formed on the optical transparent film on the basis of the first marker. And a plate underfilm is formed on the optical transparent film.
Thereafter, the part of the plate underfilm on the optical transparent film above the first marker is milled on the basis of the second marker.
Next, a resistframe is formed on the part of the optical transparent film including the plate underfilm above the first thin film element on the basis of the first marker which is visible from the removed area of the plate underfilm via the optical transparent film. Since the part of the plate underfilm above the first marker are removed from on the optical transparent film by milling, an exposing apparatus can recognize the first marker via the optical transparent film. Therefore, the photolithography process to form the resistframe can be performed on the basis of the first marker visible via the optical transparent film. As a result, the resistframe can be aligned for the first thin film element precisely and stably.
Thereafter, a plate film is formed on the part of the plate underfilm enclosed by the resistframe. After the resistframe is removed, the plate underfilm is patterned alongside the pattern of the plate film. As a result, the patterned plate film can be aligned for the first thin film element precisely and stably.
 less than Third type of forming method greater than 
The third type of forming method includes the following steps.
First of all, an optical transparent film is formed on a support so as to cover a first thin film element and marker on the support, and then, flattened.
Subsequently, a resist-cover is formed on the part of the optical transparent film above the marker by a photolithography process. Thereafter, an optical opaque film is formed on the optical transparent film and the resist-cover Then, the resist-cover is removed from the optical transparent film. The resist-cover can be easily removed by a lift-off method. In removing the resist-cover, the part of the optical opaque film thereon is also removed. Therefore, an exposing apparatus can recognize the marker via the optical transparent film.
Subsequently, the optical opaque film is patterned by a photolithography process to form a second thin film element. In this case, the photolithography process can be carried out on the basis of the marker which is visible via the optical transparent film. Therefore, the first and second thin film elements which are positioned vertically can be aligned precisely and stably.
 less than Fourth type of forming method greater than 
The fourth type of forming method includes the following steps.
First of all, an optical transparent film is formed on a support so as to cover a first thin film element and a first marker on the support, and then, flattened.
Then, a second marker is formed on the optical transparent film on the basis of the first marker. And an optical opaque film is formed on the optical transparent film.
Thereafter, the part of the optical opaque film on the optical transparent film above the first marker is milled on the basis of the second marker. Since the milling is carried out so that the first marker can be recognized via the optical transparent film, it is not required to be done precisely. Therefore, there is no problem in the milling on the basis of the second marker.
Then, the optical opaque film is patterned by a photolithography process to form a second thin film element. This photolithography process is carried out on the basis of the first marker which is visible via the optical transparent film.
As mentioned above, since the part of the optical opaque film above the first marker are removed from the optical transparent film by milling, an exposing apparatus can recognize the first marker via the optical transparent film. Therefore, the photolithography process to form the second thin film element can be performed on the basis of the first marker visible via the optical transparent film. As a result, the first and second thin film elements which are positioned vertically can be aligned for the first thin film element precisely and stably.
The other objects, configurations and advantages will be explained in detail, with reference to the attaching drawings in embodiments.